Expansion bolt and pivot and swivel mechanism therefor

ABSTRACT

An expansion bolt and pivot and swivel mechanism therefor. The expansion bolt may have a base and a plurality of radially spreadable elongate elastic members cantileveredly projecting from the base at respective points of joinder to the base and terminating in respective spoons at respective points of joinder of the spoons, wherein the elongate elastic members have respective radially defined thicknesses at the points of joinder to the base that are substantially less than the corresponding thicknesses of the base, and respective radially defined thicknesses at the points of joinder of the spoons that are substantially less than the corresponding thicknesses of the spoons. The pivot and swivel mechanism may have a ring element that includes two spaced apart leg members having foot portions that turn to extend toward each other, the foot portions having respective, spaced-apart relatively enlarged ends; a swivel housing element having an open end for receiving and at least partially containing the ends of the foot portions so that the ring element can be substantially freely rotated about a pivot axis; and a capping element adapted for interlocking with the open end of the swivel housing element, the capping element having a bottom surface portion of radial symmetry about a swivel axis that is distinct from the pivot axis.

FIELD OF INVENTION

The present invention relates to an expansion bolt, particularly forengaging holes in structures, typically to provide an anchor point fortethering a worker to the structures, and a pivot and swivel mechanismthat can be used in an expansion bolt but which can also be used inother applications as well.

BACKGROUND

An exemplary prior art expansion bolt is disclosed in U.S. Pat. No.7,357,363. FIGS. 1 and 2 are taken from that patent, showing anexpansion bolt 10 for engaging cylindrical holes, typically though notnecessarily drilled or bored into concrete or other constructionsubstrate. Referring to FIG. 1, as is common in the art the expansionbolt 10 includes a cable 12 having a center chock 13 at a distal endthereof. The center chock has an outer surface 13 a and a cooperatingouter chocks 16 and 17 provided to engage the center chock and toaccommodate linear movement of the cable 12 along a longitudinal axis“L.”

The outer chock assembly 15 may include the two outer chocks referencedas 16 and 17. Each outer chock is preferably attached to a collar 20through a respective elongate control cable or rod 22 that permitsmoving the outer chock along the longitudinal axis with respect to theinner chock by pushing on the collar 20.

The outer chocks 16 and 17 have inner surfaces 16 a and 17 a againstwhich the outer surface 13 a of the center chock 13 slides as a resultof relative linear movement of the cable with respect to the collar 20.Particularly, when the collar 20 is pulled against the bias of acompression spring 32 along the axis “L” in the direction of the arrowwith respect to the cable, the outer chocks can move radially inwardly,to provide a contracted configuration of the expansion bolt; andconversely, when the collar is pushed back by the spring 32 in theopposite direction the outer chocks are forced radially outwardly, toprovide an expanded configuration of the expansion bolt. When introducedinto a hole, the outward expansion of the outer chocks is resisted bythe inner surface of the hole, anchoring the expansion bolt in the hole;whereas the contracted configuration permits removing the expansion boltfrom the hole.

FIG. 2 shows the center and outer chocks wedged in a hole 61. In thisconfiguration, the chocks cannot be pulled out from the hole under anaxial (i.e., directed along the longitudinal axis) load, such as may beimposed by a construction worker who is tethered to the expansion boltand who has fallen. Expansion bolts are designed to support axial loadsof at least 900 pounds for this purpose.

FIG. 2 also shows a “cleaning bushing” 62 that is used for removing theexpansion bolt from the hole once the chocks have been wedged into thehole. A hammer (not shown) is used to hammer on a punch to provide animpact force to the cleaning bushing, that knocks the center chock 14forward relative to the outer chocks 16 and 17, thereby loosening thegrip between the outer chocks and the interior surface 64 of the holesufficient to allow a user to pull the expansion bolt out of the hole.

Returning to FIG. 1, a loop 30 is provided at a proximal end of thecable 12 providing a hand-hold for a user of the expansion bolt 10, anda means for moving the cable with respect to the collar 20. Acompression spring 32 is provided between the loop 30 and the collar 20,to bias the device into its expanded configuration. The compressionspring is important. Its bias protects against small amounts of slippageout of the hole that may otherwise occur as a result of the surface ofthe hole crumbling or deforming in response to the load applied to theloop 30. Even very small amounts of slippage may lead to a catastrophicloss of grip with potentially very serious consequences. It also allowsfor single-handed operation of the expansion bolt. With the spring 32 inplace and the expansion bolt grasped in one hand like a syringe, e.g.,the index and middle fingers are positioned on the collar 20, at “A₁”and “A₂” respectively, and the thumb in the loop 30 at “B,” the collarcan be pulled back against the spring bias for inserting the expansionbolt in to the hole and simply released for chocking the expansion boltsnugly into the hole.

The cable 12 extends out of the hole and supports the load. Because itis a cable, it is flexible and can twist and bend elastically when it isloaded, to convert bending stress into axial stress and thereby tominimize the effects of what is known in the art as a “cross-loading”condition in which the expansion bolt would otherwise be placed undersignificant bending stress.

It is possible to use a “concrete anchor” to provide the anchoringfunction of an expansion bolt. FIG. 3 shows a typical concrete “sleeveanchor” 2. The sleeve anchor is intended to be installed in a hole whichhas been drilled into a concrete structure, such as a concrete floor orwall of a building.

The sleeve anchor has a housing 4 and a threaded bolt 6, the shank ofwhich is coaxially disposed inside the housing and is able to turnrelative to the housing.

The housing 4 has a plurality of leaves (leaves 4 a, 4 b are shown)which are azimuthally separated, relative to a longitudinal axis “L” ofthe sleeve anchor, by corresponding slots (slot 4 c is shown).

The bolt 6 has a frustoconically shaped distal end 7. The bolt end 7 issized to provide for expanding the housing 4 at the leaves as the boltend is drawn up into the housing, as a result of turning the bolt.

Due to the presence of the slots between the leaves, the leaves areindividually cantilever supported by a contiguous base 5 of the housing,and bend to allow for the expansion. The bending of the leaves ispermanent, and the original configuration of the housing is notrecoverable. Concrete anchors are intended to remain permanently in thestructures in which they have been installed.

Exemplary prior art pivot and swivel mechanisms are shown and describedin applicant's U.S. Pat. No. 8,424,638. Those prior art pivot and swivelmechanisms are particularly adapted for use as dedicated anchor points;whereas it is an object of the present invention to provide such amechanism that has more general application, such as being a part of aneasily removable and reusable expansion bolt.

SUMMARY

An expansion bolt and pivot and swivel mechanism therefor is disclosedherein.

The expansion bolt may have a base and a plurality of radiallyspreadable elongate elastic members cantileveredly projecting from thebase at respective points of joinder to the base and terminating inrespective spoons at respective points of joinder of the spoons, whereinthe elongate elastic members have respective radially definedthicknesses at the points of joinder to the base that are substantiallyless than the corresponding thicknesses of the base, and respectiveradially defined thicknesses at the points of joinder of the spoons thatare substantially less than the corresponding thicknesses of the spoons.

In one embodiment, the expansion bolt comprises a housing member, acentral shaft member, and a biasing member.

The housing member defines a longitudinal axis, which defines axialdirections parallel thereto and radial directions perpendicular thereto.The housing member has a base and a plurality of radially spreadableelongate elastic members cantileveredly projecting distally from thebase at respective points of joinder of the elongate elastic members tothe base, the elongate elastic members distally terminating inrespective spoons at respective points of joinder of the spoons to theelongate elastic members.

The central shaft member extends through the housing member, and teenMates at a distal end thereof in a wedge member. The spoons define acavity for receiving the wedge member. The elongate elastic membersprovide for increasing elastically recoverable radial expansion of thecavity as a consequence of increasing relative axial translation of thewedge member into the cavity.

The biasing member is for biasing the shaft member relative to thehousing member in the direction of the increasing relative translation.

The elongate elastic members have respective radially definedthicknesses at the points of joinder of the elongate elastic members tothe base that are substantially less than the corresponding thicknessesof the base, and the elongate elastic members have respective radiallydefined thicknesses at the points of joinder of the spoons to theelongate elastic members that are substantially less than thecorresponding thicknesses of the spoons.

The expansion bolt may further comprise a ring element, a swivel housingelement, and a capping element, the ring element defining a closed orcloseable attachment aperture and attached to a proximal end of thecentral shaft member, the ring element including two spaced apart legmembers, the leg members including foot portions that turn to extendtoward each other, the foot portions having respective, spaced-apartrelatively enlarged ends, the swivel housing element providing forreceiving and at least partially containing the ends of the footportions within the swivel housing element so that the ring element canbe substantially freely rotated about a pivot axis, the swivel housingelement having a first open end, and the capping element adapted forinterlocking with the first open end of the swivel housing element, thecapping element having a bottom surface portion of radial symmetry abouta swivel axis that is distinct from the pivot axis.

The ring element may be pivotally attached to the central shaft member,to allow for pivoting the ring element about radial axis.

Alternatively or in combination, the ring element may be swivellyattached to the central shaft member, to allow for pivoting the ringelement about a longitudinal axis.

The wedge element may be swivelly attached to the central shaft member,to allow for swiveling the wedge member about a longitudinal axis.

The housing member may be formed as a single piece of material, and thehousing member and the wedge member may be integrally formed together asa single piece of material.

The biasing member may comprise a spring, so that the bias comprises aspring-bias.

The pivot and swivel mechanism may have a ring element that includes twospaced apart leg members having foot portions that turn to extend towardeach other, the foot portions having respective, spaced-apart relativelyenlarged ends; a swivel housing element having an open end for receivingand at least partially containing the ends of the foot portions so thatthe ring element can be substantially freely rotated about a pivot axis;and a capping element adapted for interlocking with the open end of theswivel housing element, the capping element having a bottom surfaceportion of radial symmetry about a swivel axis that is distinct from thepivot axis.

In one embodiment, the pivot and swivel mechanism comprises a ringelement, a swivel housing element, and a capping element.

The ring element defines a closed or closeable attachment aperture andincludes two spaced apart leg members, the leg members including footportions that turn to extend toward each other, the foot portions havingrespective, spaced-apart relatively enlarged ends.

The swivel housing element has a first open end for receiving and atleast partially containing the ends of the foot portions within theswivel housing element so that the ring element can be substantiallyfreely rotated about a pivot axis.

The capping element is adapted for interlocking with the first open endof the swivel housing element, the capping element having a bottomsurface portion of radial symmetry about a swivel axis that is distinctfrom the pivot axis.

The swivel axis may be substantially perpendicular to the pivot axis.

The swivel housing element may have a second open end opposite the firstopen end, wherein the capping element has a hole therethrough, and themechanism may further comprise a shaft extending through the hole in thecapping element and the first and second open ends of the swivel housingelement.

The shaft may be threaded proximate the second open end of the swivelhousing element, and the mechanism further comprising a nut threadedonto the threads of the shaft.

The shaft may have a ledge for receiving the capping element over thebottom surface portion thereof.

The mechanism may further comprise an annular element concentricallydisposed around the shaft and supporting the capping element.

Such annular element may be a flat washer, which may comprise Teflon.

It is to be understood that this summary is provided as a means ofgenerally determining what follows in the drawings and detaileddescription and is not intended to limit the scope of the invention.Objects, features and advantages of the invention will be readilyunderstood upon consideration of the following detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a pictorial elevation view of an exemplary prior art expansionbolt.

FIG. 2 is a cross-section of a portion of the expansion bolt of FIG. 1,shown installed in a hole.

FIG. 3 is a sectional elevation view of a typical prior art concretesleeve anchor.

FIG. 4 is an isometric view of a preferred expansion bolt according tothe present invention.

FIG. 5 is an exploded isometric view of the expansion bolt of FIG. 4.

FIG. 6 is an exploded isometric view of a first alternative expansionbolt according to the invention.

FIG. 7 is an isometric view of a worker connected to the expansion boltof FIG. 4 and is thereby tethered to a structure according to thepresent invention.

FIG. 8 is a side elevation of the expansion bolt of FIG. 4 in a state ofmanipulation by which the expansion bolt is configured for insertioninto a hole.

FIG. 9 is a cross-section of the expansion bolt of FIGS. 4 and 8 beinginserted into a hole.

FIG. 10 is the same as FIG. 9 but with the expansion bolt in ananchoring configuration, seated in the hole.

FIG. 10A is a detail view of a region of the expansion bolt of FIG. 10,showing bending of a leaf portion thereof.

FIG. 11 is a broken side view of the expansion bolt as shown in FIG. 8in the anchoring configuration shown in FIG. 10.

FIG. 12 is a cross-section of the expansion bolt as shown in FIG. 11taken a long a line 12-12 thereof.

FIG. 13 is a cross-section of the expansion bolt as shown in FIG. 11taken a long a line 13-13 thereof.

FIG. 14 is an exploded isometric view of a second alternative expansionbolt according to the invention.

FIG. 15 is an exploded isometric view of a portion of a pivot and swivelmechanism according to the present invention.

FIG. 16 is a front broken cross-section of the pivot and swivelmechanism of FIG. 15 as provided in the expansion bolt of FIG. 5, takenalong a line 16-16 thereof.

FIG. 17 is a side broken cross-section of the pivot and swivel mechanismof FIG. 15 as provided in the expansion bolt of FIG. 5, taken along aline 17-17 thereof.

FIG. 18 is an isometric cross-section of the expansion bolt of FIGS. 4and 5.

FIG. 19 is a broken isometric cross-section of the expansion bolt ofFIG. 5, viewed from a different direction than that of FIG. 18.

FIG. 20 is an isometric view of a third alternative expansion boltaccording to the present invention.

FIG. 21 is a cross-sectional side elevation of the expansion bolt ofFIG. 20 installed in a hole.

DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of the present invention may be used to provide for theadvantages of a prior art expansion bolt such as that disclosed in the'363 Patent described above in a simplified and therefore cost-reducedconfiguration, and that does not require a tool for removal. In additionor in the alternative, embodiments of the present invention may be usedto provide for the advantages of the more simply constructed prior artconcrete anchor in a reusable configuration. Thus, embodiments of thepresent invention may be used either as expansion bolts or concreteanchors, and they may have other uses as well. Such uses may include,but are not limited to, supporting workers who are performingmaintenance or construction work, and providing fall protection to suchworkers.

FIGS. 4 and 5 show a preferred expansion bolt 100 according to theinvention that provides for all the aforementioned advantages over theprior art.

With particular reference to FIG. 5, the expansion bolt 100 includes acentral shaft 112 terminating, at a proximal end “PE” of the centralshaft, in a pivot and swivel mechanism 150, and at a distal end, a wedgeelement 126. The proximal end PE of the central shaft ultimatelyterminates in a capturing tip CT₁ which is not shown in FIG. 5 but isdiscussed in connection with FIG. 17.

The central shaft 112 is coaxially received through a central hole 114 ain a cap 114, through a housing 116. The central hole 114 a is largeenough to loosely or slidable receive a shank 112 b of the central shaft112, but not so large as to allow passage of the wedge element 126.

The housing 116 houses a spring 120 which biases the housing 116relative to the central shaft 112 during use of the device as will beexplained further below. The housing 116 is captured between the cap 114and the wedge element 126. The housing 116 has a base portion 116 a and,as referenced in FIG. 4, a plurality of leaves “LV” (LVa, LVb are shown)depending from the base portion. The leaves are separated by first slots“SL₁,” (two of these first slots SL₁a, SL₁b are shown). The leavesproject as cantilevers from the base portion at respective points ofjoinder “PJ_(LV-B)” (also referenced in FIG. 9) of the leaves to thebase portion, and the first slots are defined by and between the leaves.In the preferred embodiment there are 3 leaves and 3 of the first slotsSL₁ symmetrically radially disposed about a longitudinal axis “L₁”(referenced in FIG. 8) of the expansion bolt 100, i.e., a 3-foldsymmetry in this particular embodiment. But the number and spacing ofthe leaves can be varied, and radial symmetry is not essential either.

The leaves are also preferably perforated, such as with second slots“SL₂” that, along with the first slots SL₁, provide migration paths fordust particles when the expansion bolt is installed in a hole.

The leaves LV distally terminate in respective “spoons” “SP,” which areconnected to the leaves at respective points of joinder “PJ_(LV-SP)”(also referenced in FIG. 9) of the spoons to the leaves. Theaforementioned second slots SL₂ may also be used to assist to providebending flexibility to the leaves, which is also preferably otherwiseprovided by making them thinner than the spoons as discussed furtherbelow.

FIG. 6 shows a first alternative expansion bolt 200, which is the sameas the expansion bolt 100 except the housing 116 is replaced with ahousing 216 that replaces the leaves LV of the embodiment 100 with anequivalent number of discrete elongate elastic members 225. The discreteelongate elastic members 225 may be, without implying any material orshape limitation, rods, wires, or cables, any of which may be woven ornon-woven. As for the embodiment 100, in the preferred embodiment 200there are three of the discrete members 225, one for each of the threespoons SP. The spoons SP may be the same in the embodiment 200 as in theembodiment 100 but are preferably modified at the points of joinderconnections with the elongate members 225 as shown.

For purposes herein, the term “elongate elastic member” is intended tobe generic for both the leaves LV of the embodiment 100 and the members225 of the embodiment 200. The term “elastic” is intended herein to haveits ordinary engineering meaning.

Returning to FIG. 5, expansion bolts according to the inventionpreferably include a tethering ring, here referenced as 140, forconnecting, to the expansion bolt, an additional article of hardwaresuch as a carabiner, through a retaining aperture “A” defined by thetethering ring, such as shown in FIG. 7. The tethering ring may beprovided in a standard form known in the fall-protection art as a“D-ring” but this is not essential. As shown, the aperture A would becircular over 360 degrees of arc; whereas in a D-ring, the aperture Awould be circular over more than 180 degrees of arc, but less than 270degrees of arc. Preferably, the radius of the circle defined by theaperture A is between 1.5 and 3.0 inches, more preferably between 2.0and 2.5 inches, more preferably still between 2.20-2.30 inches, and mostpreferably 2.25 inches.

For connection security, the retaining aperture A should be “closed” or“closeable.” For purposes herein, an aperture is “closeable” when itcart be placed in a closed configuration, and an aperture is in a closedconfiguration for purposes herein when it is contiguously surrounded(360 degrees) by structure, so that a ring (which by this samedefinition also has a closed aperture) encircling any portion of thestructure and passing through the aperture could not be removed from theaperture without changing the configuration of the device. As shown inpreferred embodiments, the retaining aperture A is permanently closed;whereas the corresponding apertures defined by the carabiners 42 and 46shown in FIG. 7 are closeable, and are shown in closed configurations.

FIG. 8 shows an example of how the expansion bolt 100 may be manipulatedto place it in a minimum diameter configuration, measured radially ofthe longitudinal axis L₁, so that it can be inserted into a hole withthe assistance of the cap 114.

Such a hole 9 a in a structure 9 is shown in FIGS. 9 and 10, in whichthe embodiment 100 is shown. For reference in both FIGS. 9 and 10, thelongitudinal axis L₁ of the expansion bolt 100 shown in FIG. 8 iscoincident with a longitudinal axis “L₂” of the hole 9 a.

The hole 9 a may be adapted in advance for receiving the expansion bolt,or the expansion bolt may be adapted in advance for use in an existinghole. Typically, the hole 9 a is a drilled hole and is thereforesubstantially cylindrical. But the hole 9 a could be a cast or existinghole, and the hole 9 a need not be cylindrical; the expansion bolt couldeasily be adapted for use in a square (using four leaves) or triangularshaped hole, for example. In all cases, however, the hole will have alongitudinal axis L₂ which, in the ease of a cylindrical hole, is thecylindrical axis of the hole. The longitudinal axis L₂ of the holealigns substantially with the longitudinal axis L₁ of the expansion boltas the expansion bolt 10 is inserted into the hole.

Returning to FIG. 8, the cap 114 has a flange portion 114 b with anundersurface “US,” and a reduced diameter body portion 114 c, which isreduced in diameter relative to the flange portion, the diametersmeasured radial to the longitudinal axis L₁.

In the example, a user's thumb may be positioned to press down on thetop of the pivot and swivel mechanism 150, and the user's index andmiddle fingers placed on an under-surface “US” of the flange portion 114b for pulling on the flange portion, against a spring bias provided bythe spring 120.

FIG. 9 shows the expansion bolt 100 partially inserted into the hole 9a. The expansion bolt is held as shown in FIG. 8, and the spring 120 iscompressed as a consequence of being captured between a ledge “LG₁₁₆” ofthe housing 116 and a bottom or distal portion of the pivot and swivelmechanism 150. The expansion bolt is thus caused to adopt a contracted,minimal diameter configuration, measured radially from the longitudinalaxis L₁, so that the expansion bolt can be inserted into the hole 9 awith the assistance of the cap 114.

FIG. 10 shows the expansion bolt after it has been seated in the holeand the user has let go of it. The spring 120 is allowed to extend andthereby force the central shaft 112 upwardly relative to the housing116, drawing the wedge member 126 into a cavity “CVT” defined interiorlybetween the spoons SP of the housing, thereby radially spreading thespoons so as to produce a larger diameter, expanded configuration of theexpansion bolt, which by forcing the spoons against the interior surfaceof the hole to anchor the expansion bolt in the hole defines an“anchoring configuration” of the expansion bolt in which the expansionbolt is both seated in the hole and expanded.

The spring 120 may be a coiled compression spring such as shown in,e.g., FIGS. 5 and 6, but other spring configurations could be used toachieve the same results.

FIG. 10 also shows that in the anchoring configuration of the expansionbolt, the leaves LV are caused to bend into a slight “S” configurationby their reaction to the hole, in the region indicated at “S_(LV)” (seeFIG. 10A) as a consequence of the spoons SP moving radially outwardly inresponse to receiving the wedge member 126, closing the slight gapbetween the spoons and the surface of the hole 9 a that can be seen inFIG. 9, and as a consequence of the fact that the outer surfaces of thespoons, “OS_(SP)” as referenced in FIG. 9, are substantially parallel tothe surface of the hole, before being expanded against the surface ofthe hole as shown in FIG. 10.

The wedge element 126 is typically frustoconical, as defined by itsouter surface 126 a. In that case, as suggested by comparison of FIGS.12 and 13, the inside surfaces “IS_(SP)” of the spoons SP are preferablycylindrical (not tapered), with radial curvature that matches that ofthe wedge element 126 where the wedge element is widest, nearest thedistal end “DE” of the central shaft 112 (see FIG. 5), and which istherefore less than that of the wedge element where the wedge element isnarrowest, farthest from the end DE. This provides for maximum surfacecontact between the spoons and the wedge element when the expansion boltis anchored in the hole.

As can be seen in FIGS. 9 and 10, the cylindrical inner surfaces IS_(SP)identified in FIGS. 12 and 13 are angled a small amount from thelongitudinal axis L₁, such as by about 3-5 degrees.

Staying with FIG. 5, the wedge element 126 need not be frustoconical.For example, it could be configured as a three-sided pyramid (or asanother example, a two-sided wedge), for engaging three (or, in the caseof a two-sided wedge, two) spoons having planar inner surfaces IS_(SP).The wedge element 126 may be integrally formed with the central shaft112, although this is not essential.

The tethering ring 140 is preferably connected to the central shaft 112so as to allow the tethering ring to pivot about a pivot axis “PA” thatis perpendicular to the longitudinal axis L₁ of the expansion bolt.Preferably, the tethering ring is enabled to substantially freely pivotabout the pivot axis PA through a pivot angle of at least 90 degrees,more preferably at least 170 degrees, and most preferably at least 180degrees.

It is also desirable to provide for swiveling the tethering ring 140about the longitudinal axis L₁. Providing for both pivoting andswivelling of the tethering ring is important for minimizing the effectsof cross-loading conditions as noted previously.

One way to provide a swivelling feature in expansion bolts according tothe invention is to employ a frustoconically shaped wedge member 126that is a separate part from the central shaft 112, such as in theembodiment 300 shown in FIG. 14. In the embodiment 300, the capabilityto pivot the ring 140 about the pivot axis PA is provided by aconnecting ring 112 a at the proximal end “PE” of the central shaft 112,and a pivot shaft 112 d extending through the connecting ring andthrough corresponding holes at terminating ends 140 a of the tetheringring 140. The ends of the pivot shaft may be swaged to capture the ends140 a of the tethering ring. Of course, there are many other ways toprovide for pivotally connecting the tethering to the central shaft 112,as will be readily appreciated by persons of ordinary mechanical skill.

To provide for swivelling the tethering ring in the embodiment 300, thewedge element 126 has a central hole 126 b for loosely receiving thedistal end DE of the central shaft 112 so that the wedge element canspin or swivel about the central shaft (axis L₁). For this purpose, thedistal end DE of the central shaft may have a reduced-diameter portion112 c, which is reduced in diameter relative to the diameter of theshank 112 b, the diameters measured radially, perpendicular to thelongitudinal axis L₁.

With the wedge element 126 in place, a capturing tip “CT₂” may beprovided or formed at the distal end DE of the central shaft 112, suchas by swaging the end of the central shaft, in cases where the centralshaft is formed of metal, or by an equivalent process in cases where thecentral shaft is formed of plastic, to produce in the capturing tip anouter diameter “D_(CT)” that is larger than the diameter of the centralshaft, for capturing and retaining the wedge element at the distal endof the central shaft. Of course, there are many other ways the wedgeelement 126 could be captured to the central shaft 112, as will bereadily appreciated by persons of ordinary mechanical skill.

Another way to provide for swiveling the tethering ring 140 about thelongitudinal axis L₁ is to incorporate a swivel mechanism on the centralshaft 112. Any known swivel mechanism could be used, but a preferred andnovel mechanism 150 is shown employed in the embodiment 100 of FIGS. 4and 5 that provides for both pivoting and swivelling. Details of thispivot and swivel mechanism 150 are shown in FIGS. 15-19.

With particular reference to FIG. 15, the pivot and swivel mechanism 150includes the aforedescribed ring 140 (see, e.g., the discussion of FIGS.4 and 5), a “swivel housing” 156, and a “cap” 158. The parts are shownexploded along a longitudinal axis “L₃” of the pivot and swivelmechanism, which is congruent with the axis “L₁” of the expansion bolt100 when the pivot and swivel mechanism 150 is employed therein.

The ring 140 has a closed retaining aperture “RA,” but it could bemerely closeable. The ring 140 also has two leg portions “140L,” namely“140L₁” and “140L₂;” the leg portions 140L each have correspondinginwardly turned foot portions “140F,” namely “140F₁” and “140F₂;” andthe foot portions each live enlarged, flanged ends “140FE,” namely,“140FE₁” and “140FE₂.” The foot portions and flanged ends arecylindrical to allow for pivoting the ring 140 about a pivot axis “PA,”and the leg portions define a clearance aperture “CA” therebetween inthe ring 140 so that when the ring is pivoted about the pivot axis itcan clear the swivel housing 156.

The swivel housing 156 has two leg openings “LO” (only one is visible inFIG. 15) for receiving the leg portions 140L of the ring 140. The width“W” of each leg opening LO is sufficient for receiving the correspondingleg portion 140L, but smaller than the diameter of the flanged ends 140FE to provide for partial capture of the flanged ends within the swivelhousing 156. Capture of these ends inside the swivel housing iscompleted by fitting the cap 158 to a base “B₁₅₆” of the swivel housing,to result in the configuration shown in FIG. 4.

As best seen in FIG. 16, with the cap 158 fitted to the swivel housing156, and with the flanged ends 140F of the ring 140 capturedtherebetween, there remains space for the central shaft 112 about which(axis L₂) the ring 140 can swivel. The central shaft 112 may have aledge “LG₁₁₂” on which the cap 158 may be seated (see also FIG. 5).

FIG. 18 shows the pivot and swivel mechanism 150 as employed in theexpansion bolt 100, sectioned for clarity. This view shows the swivelhousing 156 capped with the cap 158 as it appears in FIG. 15. Withreference to the latter, the cap 158 has a proximally extending, annularcup portion “C₁₅₈” for interfacing with the base B₁₅₆ of the swivelhousing.

It is an outstanding feature of this interface that the swivel housing156 “interlocks” into the cup portion of the cap 158, and consequentlyresists prying the swivel housing 156 apart from the cap 158, such aswhere the ring 140 is loaded downwardly, perpendicular to the axis L₂.

As best seen in FIG. 17, this interlocking feature may be provided by aninterface between the base B₁₅₆ of the swivel housing and the cupportion C₁₅₈ of the cap that becomes progressively narrower in theradial dimension (see the angle θ) with increasing elevation in thedirection in which the swivel housing would be extracted from the cap.This interlocking feature is generally defined for purposes herein asbeing complementary mating structures on the base and cap that provideresistance to pulling these two elements apart along the longitudinalaxis L₃ (FIG. 16). As will be readily appreciated by persons of ordinarymechanical skill, there are many other ways these two elements could beinterlocked together, such as by providing complementary screw threadson the two elements, or by providing complementary “snap” fittingfeatures on the two elements such as corresponding ribs andrib-receiving voids.

Returning to FIG. 18, the swivel housing 156 may be enabled to resistbeing pulled out of the cap 158 in response to a force or component offorce that is applied to the ring 140 axially, i.e., parallel to theaxis L₂, by a nut 160 that is threaded onto the distal end of thecentral shaft 112. With additional reference to FIG. 17, the nut 160 maybe further captured by the capturing tip CT₁ that was mentioned brieflyabove in connection with its omission from FIG. 5, that may be formed inthe same manner as the capturing tip “CT₂” described previously forcapturing the wedge element 126 to the central shaft 112 in theembodiment 200 of the expansion bolt. Of course, there are many otherways the central shaft 112 could be adapted to resist thrust loadsapplied to the swivel housing, as will be readily appreciated by personsof ordinary mechanical skill.

With reference to FIG. 16, the cap 158 can be made radially symmetricabout the axis L₃ where it contacts the ledge LG₁₁₂ to provide thedesired swiveling capability; no additional structure is necessary.However, with additional reference to FIG. 19, it may facilitate thisswiveling capability to provide a “Teflon” washer 165, which may be butwhich need not necessarily be a flat washer, to provide a larger surfaceBS₁₅₈ to ride on, which may be but need not necessarily be supported bythe spring 120. This washer may also be used to keep the end of thespring 120 off the ledge LG₁₁₂.

As noted previously in connection with FIGS. 8-10, the expansion bolt100 may be manipulated to place it in a minimum diameter configurationso that it can be inserted into a hole 9 a in a structure 9 with theassistance of the cap 114. This will be explained further in thediscussion to follow, with the understanding that this discussionapplies equally as well to the embodiments 200 and 300.

As indicated in FIG. 5, the cap 114 has a floor “FL;” and as indicatedin FIG. 10, this floor has a top surface “TS₁₁₄” and a bottom surface“BS₁₁₄.” In the embodiment shown, both of these surfaces are annular,but that is not essential.

Normally, the outer face 9 b of the concrete structure in proximity tothe hole is flat; so it is normally preferable to provide that thebottom surface BS₁₁₄ of the cap 114 is flat, for seating on thistypically flat outer surface of the structure. But in any case, at leastsome portions of the bottom surface of the cap should extend radiallyoutwardly of the longitudinal axis L₃ far enough, relative to the sizeof the hole 9 a, to rest on the outer face 9 b of the structure 9, asshown in FIG. 16.

Also as best seen in FIG. 5, the base portion 116 a of the housing 116has a flange “FL₁₁₆” at a proximal end thereof. With particularreference to FIG. 10, the flange FL₁₃₆ has a bottom surface“BS_(FL-116)” that is adapted to rest on the top surface TS₁₁₄ of thecap 114, as shown in both FIGS. 9 and 10. Contact between these surfacesis maintained by compression of the spring 120.

In contrast to the prior art concrete anchor, the elongate elasticmembers of the housing 116 are adapted or configured to bend elasticallyin repeated normal use, so that the expansion bolt can be removed fromthe hole and reused if it has not been involved in arresting a fall; andthe ends of the leaves are adapted or configured to so that they willnot crush if there is a fall.

As best seen in FIG. 9, these features may be facilitated by use of aconfiguration of the leaves according to which the leaves LV have aradial thickness “t₁” that is thinner than the minimum radial thickness“t₂” of the spoons SP. A relatively small thickness t₁ provides forgreater bending elasticity, and a relatively large thickness t₂ providesfor greater crush resistance. Normally the t₂ dimension is the sameregardless of the t₁ dimension. Providing for both the desired bendingelasticity and crush resistance using leaves of constant thickness ispossible, but there are undesirable consequences such as a need tosubstantially increase the overall length of the leaves LV (distance“OL” in FIG. 8).

Preferably, where such differential in thickness is provided, t₁ is nomore than 90% of t₂, and more preferably t₁ is no more than 70% of t₂.Generally, increasing the dimension t₂ provides for greater crushresistance while decreasing the dimension t₁ provides for greaterbending elasticity. Both greater crush resistance and greater bendingelasticity reduce the possibility of permanent deformation and thusincrease the effectiveness of the expansion bolt for reuse.

The same result could be provided in ways other than by use of differentmaterial thicknesses of the leg portions and the ends of the leaves. Forexample, the same or similar result could be provided by joiningdifferent materials; however, the use of leaves configured as shown withdifferential thicknesses allows for forming the leaves integrally ormonolithically with the body, in a single piece of material, whichprovides manufacturing cost advantages over prior art expansion bolts.

Preferably, the spoons SP have sufficient crush resistance to providethat the expansion bolt can support an axial load, i.e., a load directedalong the longitudinal axis L₁, of at least 450 pounds, withsubstantially no plastic deformation, i.e., no plastic deformation thatwould render, to a person of ordinary skill, reuse of the expansion boltfor supporting the same load, imprudent.

It was noted previously that leaves LV with differential thicknesses canbe formed integrally or monolithically with the body, in a single pieceof material, which provides manufacturing cost advantages over prior artexpansion bolts. The body can be formed of a metal, plastic, orcomposite material.

Likewise, the central shaft 112 can be formed as an integral ormonolithic single piece of material, such as metal, plastic, orcomposite material, which likewise provides manufacturing costadvantages over prior art expansion bolts, which typically employbraided cables.

It is also advantageous to provide that the central shaft 112 is“rigid,” i.e., sufficient that a compression force applied to thecentral shaft, when it is otherwise unloaded, by pushing on the centralshaft (such as by hammering on the capturing tip CT₁ of the tetheringring 140) in the load-releasing direction “LRD” shown in FIG. 8, willforce the wedging member 126 out of the aformentioned cavity CVT, toloosen the hold or grip the expansion bolt has on the interior of thehole into which it is installed. This provides the outstanding advantageof allowing a user to remove the expansion bolt without need for theprior art “cleaning bushing” 62 (FIG. 2) and punch, shown and describedin the '363 Patent.

Achieving the desired rigidity in the central shaft 112 is facilitatedby forming it as an integral, monolithic, or non-woven structure.Sufficient rigidity could be achieved with a central shaft 112 that iseither partially or wholly in the form of a braided or woven cable, butcables by nature are less effective to resist compressive loads. So ifthe central shaft 112 were to be provided either partially or wholly inthe form of a cable, that cable should be relatively thick, tocompensate for its relative lack of resistance to buckling.

FIG. 7 shows the expansion bolt 100 installed in the structure 9, andbeing used to tether a worker to the structure. A first carabiner 42 maybe connected to the ring 140 of the cap 114 and one end of a lanyard 44.The other end of the lanyard 44 may be connected by a second carabiner46 to a D-ring 48 which in turn connects to a harness 50 worn by theworker. Other equivalent structures as known in either the recreationalclimbing or the industrial fall protection arts could be used forconnecting the worker to the expansion bolt 100.

FIGS. 20 and 21 show another alternative expansion bolt 400 thatreplaces the spring 120 of the embodiment 100 with an alternativebiasing member which is a cam 402. The cap 114 may be retained, or not,and the cam could be used in combination with the spring 120. The cammay be set by hand in the direction of the arrow in FIG. 21 to produce abias equivalent to that of the spring 120, for drawing the central shaft112 upwardly relative to the spoons SP and thereby radially spreadingthe spoons against the inner surface of the hole; and/or it may be setor urged to stay in place by gravity.

It may be noted that the anchoring bolt in its unloaded anchoringconfiguration as shown in FIG. 10 is only subject to whatever anchoringforce can be developed by the spring 120, but of course, the anchoringforce will increase significantly if the worker falls. Although it maybe possible to reuse the expansion bolt after such an event, this is notnormally intended.

While expansion bolts according to the invention are typically used forinstallation in holes in concrete structures for the purpose oftethering a worker engaged in construction work on the structure, theycould be used for other attachment or connecting purposes, in holes inother types of structures or substrates, man-made or natural.

It is to be understood that the pivot and swivel mechanism is notlimited to use in expansion bolts generally or expansion bolts accordingto the present invention particularly. It may be used in any applicationin which a pivot and swivel mechanism or feature is desired.

It is to be understood that, while a specific expansion bolt and pivotand swivel mechanism therefor has been shown and described as beingpreferred, variations may be made, in addition to those alreadymentioned, without departing from the principles of the invention.

The terms and expressions which have been employed in the foregoingspecification are used therein as terms of description and not oflimitation, and there is no intention in the use of such terms andexpressions to exclude equivalents of the features shown and describedor portions thereof, it being recognized that the scope of the inventionis defined and limited only by the claims which follow.

The invention claimed is:
 1. An expansion bolt, comprising: a housingmember defining a longitudinal axis, the longitudinal axis definingaxial directions parallel thereto and radial directions perpendicularthereto, the housing member having a base and a plurality of radiallyspreadable elongate elastic members cantileveredly projecting distallyfrom the base at respective points of joinder of the elongate elasticmembers to the base, the elongate elastic members distally terminatingin respective spoons at respective points of joinder of the spoons tothe elongate elastic members; a central shaft member extending throughthe housing member and terminating at a distal end thereof in a wedgemember, the spoons defining a cavity for receiving the wedge member, theelongate elastic members providing for increasing elasticallyrecoverable radial expansion of the cavity as a consequence ofincreasing relative axial translation of the wedge member into thecavity; and a biasing member for biasing the shaft member relative tothe housing member in the direction of said increasing relativetranslation, wherein the elongate elastic members have respectiveradially defined thicknesses at the points of joinder of the elongateelastic members to the base that are substantially less than thecorresponding thicknesses of the base, and the elongate elastic membershave respective radially defined thicknesses at the points of joinder ofthe spoons to the elongate elastic members that are substantially lessthan the corresponding thicknesses of the spoons, and wherein thehousing member is integrally formed as a single piece of material. 2.The expansion bolt of claim 1, further comprising a ring element, aswivel housing element, and a capping element, the ring element defininga closed or closeable attachment aperture and attached to a proximal endof the central shaft member, the ring element including two spaced apartleg members, the leg members including foot portions that turn to extendtoward each other, the foot portions having respective, spaced-apartrelatively enlarged ends, the swivel housing element providing forreceiving and at least partially containing the ends of the footportions within the swivel housing element so that the ring element canbe substantially freely rotated about a pivot axis, the swivel housingelement having a first open end, and the capping element adapted forinterlocking with the first open end of the swivel housing element, thecapping element having a bottom surface portion of radial symmetry abouta swivel axis that is distinct from the pivot axis.
 3. The expansionbolt of claim 2, wherein the biasing member comprises a spring, so thatthe bias comprises a spring-bias.
 4. The expansion bolt of claim 1,further comprising a ring element pivotally attached to the centralshaft member, to allow for pivoting the ring element about a radial axisperpendicular to the longitudinal axis.
 5. The expansion bolt of claim1, further comprising a ring element swivelly attached to the centralshaft member, to allow for swivelling the ring element about thelongitudinal axis.
 6. The expansion bolt of claim 5, wherein the ringelement is pivotally attached to the central shaft member, to allow forpivoting the ring element about a radial axis perpendicular to thelongitudinal axis.
 7. The expansion bolt of claim 6, wherein the biasingmember comprises a spring, so that the bias comprises a spring-bias. 8.The expansion bolt of claim 5, wherein the biasing member comprises aspring, so that the bias comprises a spring-bias.
 9. The expansion boltof claim 1, wherein the wedge member is swivelly attached to the centralshaft member, to allow for swiveling the wedge member about thelongitudinal axis.
 10. The expansion bolt of claim 1, wherein thecentral shaft member and the wedge member are integrally found togetheras a single piece of material.
 11. The expansion bolt of claim 1,wherein the biasing member comprises a spring, so that the biascomprises a spring-bias.